The Ringer - S1-E1
Continuity mistake: When the Moblins attack Link in his room through a sort of trap door, the hole that is the door keeps changing locations, shapes, and the tiles around it all throughout the fight. Some points even disappearing entirely. (00:01:25 - 00:03:40)
Love 'Em and Leave 'Em - S1-E8
Continuity mistake: After Luigi says "Let's play cupid," he peeks around the corner along with Peach and Toad down at Mario going down the aisle with his "bride-to-be." Luigi, as expected, has been wearing green all episode, but when you see them peeking around the corner, Luigi's hat has become red. In the very next shot showing Luigi from behind, his hat has returned to green. (00:14:40)
What Price Gloria? - October 16, 1961 - S2-E4
Continuity mistake: When Sam goes out of the window to save Gloria, part of the ledge breaks off, but in the near shots it is broken off almost to the corner near Gloria, while in the shots from below most of the ledge is still intact. (00:35:45)
Continuity mistake: In the shot of the railway bridge after it collapses completely, look closely near the end of the tracks, and you'll see a small flame that was caused by the sparks. But in the next shot of the bridge, the flame has disappeared.